Thrombin, a coagulation protease, activates G protein-coupled protease-activated receptors (PARs) which in turn induce cell activation such as platelet aggregation and proliferation of vascular smooth vessel cells. See Coughlin, Proc. Natl. Acad. Sci. USA, 1999, 96: 11023-11027. Aggregation of the activated platelets contributes to pathogenesis of many diseases, e.g., atherosclerosis, myocardial infarction, unstable angina pectoris, and thrombosis. It is therefore desirable to discover a drug which can treat such diseases by specifically inhibiting the activation of PARs, e.g., by means of inhibiting thrombin.
This invention relates to a method of treating a disorder related to PAR-induced platelet aggregation. The method includes administering to a subject -n need thereof a compound having a pyrazolyl core and three aryl groups: (1) a first aryl group, via an alkylene linker, bonded to 1-N of the pyrazolyl core, (2) a second aryl group fused at 4-C and 5-C of the pyrazolyl core, and (3) a third aryl group bonded directly to 3-C of the pyrazolyl core. Each of these three aryl groups, independently, is phenyl, thienyl, furyl, or pyrrolyl, which is optionally mono-substituted or multi-substituted with halo (e.g., xe2x80x94Cl), alkyl (e.g., xe2x80x94C5H11), carboxyl, alkoxycarbonyl [e.g., xe2x80x94(Cxe2x95x90O)xe2x80x94Oxe2x80x94C5H11], thiocarbonyl [e.g., xe2x80x94(Cxe2x95x90O)xe2x80x94Sxe2x80x94C4H9], aminocarbonyl [e.g., xe2x80x94(Cxe2x95x90O)xe2x80x94N(C3H7)2], hydroxyalkyl (e.g., xe2x80x94C6H12OH), alkoxyalkyl (e.g., xe2x80x94C3H6xe2x80x94Oxe2x80x94iC4H9), amino, aminoalkyl [e.g., xe2x80x94C3H6N(C3H7)2], thioalkyl (e.g., xe2x80x94C4H8SC4H9), or oxyalkoxy (e.g., xe2x80x94OCH2CH2Oxe2x80x94 as a disubstituent). The compound is administered to the subject in an amount effective for treating the disorder,
Shown below is a formula which encompasses a number of the fused pyrazolyl compounds described above: 
Formula (I) includes a pyrazolyl core and three aryl groups, i.e., Ar1, Ar2, and Ar3, as the three aryl groups described above. Each of Ar1, Ar2, and Ar3, independently, is phenyl, thienyl, furyl, or pyrrolyl; each of R1, R2, R3, R4, R5, and R6, independently, is H, halo, xe2x80x94R, xe2x80x94C(xe2x95x90O)OH, xe2x80x94C(xe2x95x90O)OR, xe2x80x94C(xe2x95x90O)SH, xe2x80x94C(xe2x95x90O)SR, xe2x80x94C(xe2x95x90O)NRRxe2x80x2, xe2x80x94ROH, xe2x80x94RORxe2x80x2, xe2x80x94RSH, xe2x80x94OR, xe2x80x94OH, xe2x80x94SR, xe2x80x94SH, xe2x80x94NRRxe2x80x2, xe2x80x94NHR, xe2x80x94RNRxe2x80x2Rxe2x80x3, xe2x80x94RNHRxe2x80x2, or xe2x80x94RSRxe2x80x2, or R1 and R2 together, R3 and R4 together, or R5 and R6 together, are xe2x80x94OROxe2x80x94, wherein each of R, Rxe2x80x2, and Rxe2x80x3, independently, is C1-4alkyl; and n is 1, or 2, or 3.
A subset of the compounds of formula (I) are featured by that n is 1, Ar3 is phenyl, and each of R5 and R6, independently, is H, halo, xe2x80x94R, xe2x80x94C(xe2x95x90O)OH, xe2x80x94C(xe2x95x90O)OR, xe2x80x94C(xe2x95x90O)SH, xe2x80x94C(xe2x95x90O)SR, xe2x80x94C(xe2x95x90O)NRRxe2x80x2, xe2x80x94ROH, xe2x80x94RORxe2x80x2, xe2x80x94RSH, xe2x80x94NRRxe2x80x2, xe2x80x94NHR, xe2x80x94RNRxe2x80x2Rxe2x80x3, xe2x80x94RNHRxe2x80x2, or xe2x80x94RSRxe2x80x2, or R5 and R6 together are xe2x80x94OROxe2x80x94.
Another subset of the compounds of formula (I) are featured by that n is 1, Ar3 is furyl, and each of R5 and R6, independently, is H, halo, xe2x80x94R, xe2x80x94C(xe2x95x90O)OH, xe2x80x94C(xe2x95x90O)OR, xe2x80x94C(xe2x95x90O)SH, xe2x80x94C(xe2x95x90O)SR, xe2x80x94C(xe2x95x90O)NRRxe2x80x2, xe2x80x94ROH, xe2x80x94RORxe2x80x2, xe2x80x94RSH, xe2x80x94NRRxe2x80x2, xe2x80x94NHR, xe2x80x94RNRxe2x80x2Rxe2x80x3, xe2x80x94RNHRxe2x80x2, or xe2x80x94RSRxe2x80x2, or R5 and R6 together are xe2x80x94OROxe2x80x94.
Set forth below are some specific examples of the compounds which can be used to practice the method of this invention: 1-benzyl-3-(3xe2x80x2-ethoxycarbonyl)phenyl-indazole, 1-benzyl-3-(3xe2x80x2-hydroxymethyl)phenyl-indazole, 1-benzyl-3-(5xe2x80x2-diethylaminomethyl)-furyl-indazole, 1-benzyl-3-(5xe2x80x2-methoxymethyl)furyl-indazole, 1-benzyl-3-(5xe2x80x2-hydroxymethyl)furyl-6-methyl-indazole, 1-benzyl-3-(5xe2x80x2-hydroxymethyl)-furyl-indazole, 1-benzyl-3-(5xe2x80x2-hydroxymethyl)-furyl-6-fluoro-indazole, 1-benzyl-3-(5xe2x80x2-hydroxymethyl)-furyl-6-methoxy-indazole, and 1-benzyl-3-(5xe2x80x2-hydroxymethyl)-furyl-5, 6-methylenedioxo-indazole.
The structures of 1-benzyl-3-(3xe2x80x2-ethoxycarbonyl)phenyl-indazole and 1-benzyl-3-(5xe2x80x2-diethylaminomethyl)-furyl-indazole are shown below with the atoms on the aryl groups numbered: 
For brevity, the fused pyrazolyl compounds described above include their pharmaceutically acceptable salts and prodrugs, if applicable. Such a salt can be formed between a positively charged substituent (e.g., amino) in a fused pyrazolyl compound and a negatively charged counterion (e.g., chloride, bromide, iodide, sulfate, nitrate, phosphate, or acetate). Likewise, a negatively charged substituent (e.g., carboxylate) in a fused pyrazolyl compound can form a salt with a positively charged ion (e.g., sodium ion, potassium ion, magnesium ion, calcium ion, or an ammonium cation such as tetramethylammonium ion). Examples of the salts that can be used in the method of this invention include a hydrochloride salt of 1-benzyl-3-(5xe2x80x2-aminomethyl)furyl-indazole and a sodium salt of 1-benzyl-3-(3xe2x80x2-carboxyl)phenyl-indazole. Examples of the prodrugs include esters and other pharmaceutically acceptable derivatives, which, upon administration to a subject, are capable of providing fused pyrazolyl compounds described above.
A fused pyrazolyl compound is formulated into a pharmaceutical composition before it is administered to a subject in need of treatment of a disorder related to PAR-induced cell activation (e.g., atherosclerosis, myocardial infarction, unstable angina pectoris and thrombosis). Thus, also within the scope of the invention is the composition which contains an effective amount of the compound (or its salt) and a pharmaceutically acceptable carrier for use in treating a disorder or disease aforementioned. Examples of the carriers include colloidal silicon dioxide, magnesium stearate, cellulose, sodium lauryl sulfate, and DandC Yellow# 10. The invention also relates to the use of such a composition for the manufacture of a medicament for the treatment of above-mentioned disorders or diseases.
It was unexpected that the method of this invention specifically inhibits PAR-induced cell activation, e.g., platelet aggregation, with no or little inhibitory effect on that induced by other platelet activators. Other advantages or features of the invention will be apparent from the following detailed description of several embodiments, and also from the appending claims.
This invention relates to using a fused pyrazolyl compound to treat a disorder caused by PAR-induced cell activation.
A method of synthesizing the fused pyrazolyl compound is as follows: An aryl aryl ketone is first prepared by coupling an arylcarbonyl chloride with another aryl compound. Each aryl compound is optionally mono- or multi-substituted. The ketone then reacts with an arylalkylhydrazine, the aryl group of which is also optionally mono- or multi-substituted, to form a hydrazone containing three aryl groups. The hydrazone is transformed into a fused pyrazolyl compound. In the fused pyrazolyl compound, an aryl group is connected to 1-N of the pyrazolyl core via an alkylene linker, another aryl group is fused at 4-C and 5-C of the pyrazolyl core, and the third aryl group is directly connected to 3-C of the pyrazolyl core. Derivatives of the fused pyrazolyl compound may be obtained by modifying the substituents on any of the aryl groups.
Synthesis of three types of fused pyrazolyl compounds, i.e., 1-benzyl-3-furyl-indazole, 1-benzyl-3-phenyl-indazole, and thienylpyrazole.
Shown in Scheme 1 below is a method of synthesizing five 1-benzyl-3-furyl-indazole compounds, indicated as (1)-(5), all of which can be used to practice the method of the invention. 
As shown in Scheme 1,5xe2x80x2-methoxycarbonyl-2-furyl phenyl ketone, prepared by coupling methyl 2-furoate with benzoyl chloride, reacts with benzylhydrazine to form a benzylhydrazone as a mixture of E- and Z-form isomers. The isoform mixture is then treated with a mixture of Pb(OAc)4 and BF3/Et2O in CH2Cl2 at room temperature, via a same azo intermediate, to give compound (1). The methoxycarbonyl group in compound (1) can be hydrolyzed with NaOH to carboxylic acid group to form compound (2). Alternatively, the methoxycarbonyl group can be reduced with Ca(BH4)2 in THF to hydroxymethyl group to form compound (3). Compound (3) can be successively treated with BCl3 and diethylamine to obtain an N,N-diethylaminomethyl derivative, i.e., compound (4). Optionally, compound (3) can also be successively treated with BCl3 and methanol to obtain a methoxymethyl derivative, i.e., compound (5). Although not shown in the scheme, derivatives of compounds (1)-(5) can be obtained by using other 2-furoates, benzoyl chlorides, or benzylhydrazones, in which the aryl group is mono- or multi-substituted.
1-Benzyl-3-phenyl-indazole compounds can be prepared by following the reaction procedure shown in Scheme 1 except that benzophenone, optionally mono- or multi-substituted, is used instead of 2-furyl phenyl ketone. As an initial step, benzophenone is oxidized with CrO3 to form benzoylbenzoic acid. The benzoylbenzoic acid is then treated with ethanol to form ethyl benzoylbenzoate, which can be transformed into 1-benzyl-3-phenyl-indazole. 1-Benzyl-3-phenyl-indazole can be further transformed into its derivatives by modifying the substituent(s) on the three aryl groups, if applicable.
Fused pyrazolyl compounds containing a thienopyrazole moiety can also be prepared by following the synthetic method shown in Scheme 1, except that 2-thienyl aryl ketone is used instead of 2-furyl phenyl ketone. The mono- or multi- substitutents, if any, of the thienopyrazolyl compounds thus obtained, can be further modified to afford additional thienopyrazolyl compounds.
An effective amount of a fused pyrazolyl compound or its salt is formulated with a pharmaceutically acceptable carrier to form a pharmaceutical composition before administered to a subject in need of treatment of a disorder related to PAR-induced platelet aggregation. xe2x80x9cAn effective amountxe2x80x9d refers to the amount of the compound which is required to confer therapeutic effect on the treated subject. The interrelationship of dosages for animals and humans (based on milligrams per meter squared of body surface) is described by Freireich et al., Cancer Chemother. Rep., 1966, 50, 219. Body surface area may be approximately determined from height and weight of the patient. See, e.g., Scientific Tables, Geigy Pharmaceuticals, Ardley, New York, 1970, 537. Effective doses will also vary, as recognized by those skilled in the art, depending on the route of administration, excipient usage, and possibility of co-usage with other therapeutic treatments including use of other anti-platelet aggregation agents.
The pharmaceutical composition may be administered via a parenteral route, e.g., topically, subcutaneously, intraperitoneally, intramuscularly, and intravenously. Examples of parenteral dosage forms include aqueous solutions of the active compound, in an isotonic saline, 5% glucose, or any other well-known pharmaceutically acceptable carrier. Solubilizing agents, such as cyclodextrins, or other solubilizing agents well known to those familiar with the art, can also be included in the pharmaceutical composition.
A fused pyrazolyl compound to be used to practice the method of the invention can be formulated into dosage forms for other routes of administration (e.g., orally, mucosally, or percutaneously) utilizing well-known methods. The pharmaceutical composition can be formulated, for example, in dosage forms for oral administration in a capsule, a gel seal, or a tablet. Capsules may comprise any well-known pharmaceutically acceptable material such as gelatin or cellulose derivatives. Tablets may be formulated in accordance with the conventional procedure by compressing mixtures of the active compounds, a solid carrier, and a lubricant. Examples of solid carriers include starch and sugar bentonite. The compound can also be administered in a form of a hard shell tablet or capsule containing, for example, lactose or mannitol as a binder, a conventional filler, and a tableting agent.
A suitable in vitro inhibition assay can be used to preliminarily evaluate a fused pyrazolyl compound""s ability to inhibit cell activation induced by PARs, which are pre-activated by thrombin. For example, a platelet suspension in Tyrode""s solution can be prepared and incubated with a compound to be tested, thrombin added to trigger platelet aggregation, and the aggregation measured turbidimetrically with a light-transmission aggremometer. In vivo screening can be performed by following procedures well known in the art.